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2008 chevy
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Discussion Starter · #1 ·
Is the rear wheel HP on the TB really around 210?? :( If it's true, then it losses around 30% of it's rated power! Where is it all going to? My 335i is rated at 306 HP and its rear wheel HP is around 280, that's less then a 10% loss. I know I can't realistically compare the two, but how can the TB loss 3 times the HP? :sadcry:
 

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2002 gmc envoy_slt
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YES the RWHP is around 210 give or take, depending upon the year for a 4x4 model. Keep in mind that there is more parasitic loss in a 4x4 drive-train than in a dedicated RWD or FWD setup. We loose power at the transfer case and BOTH axles. Even with the selector set to 2WD, our trucks run the output through the gears in the transfer case. (We have a selectable HI/LO unit, so even 2HI uses several sets of gears). We also have a heavy sold rear axle, as opposed to the independent differential and half shaft setup of the BMW, which leaches off a little more power. The final inefficiency is the transmission, it is an older design, remember the 700R4, well we use basically an electronic version of that....not the most efficient tranny in the world, but reasonably durable for the amount of weight it pulls.

Since you're a 2WD model, your RWHP would be somewhat higher, having no transfer case or front drive gear. Your truck would most likely loose around 18-20% and not the near 30% us 4x4 loose. (Another reason a 2WD can tow more than a 4x4).
 

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2008 chevy
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Discussion Starter · #3 ·
YES the RWHP is around 210 give or take, depending upon the year for a 4x4 model. Keep in mind that there is more parasitic loss in a 4x4 drive-train than in a dedicated RWD or FWD setup. We loose power at the transfer case and BOTH axles. Even with the selector set to 2WD, our trucks run the output through the gears in the transfer case. (We have a selectable HI/LO unit, so even 2HI uses several sets of gears). We also have a heavy sold rear axle, as opposed to the independent differential and half shaft setup of the BMW, which leaches off a little more power. The final inefficiency is the transmission, it is an older design, remember the 700R4, well we use basically an electronic version of that....not the most efficient tranny in the world, but reasonably durable for the amount of weight it pulls.

Since you're a 2WD model, your RWHP would be somewhat higher, having no transfer case or front drive gear. Your truck would most likely loose around 18-20% and not the near 30% us 4x4 loose. (Another reason a 2WD can tow more than a 4x4).
thanks dor the info
 

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2006 chevy trailblazer_lt
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Is the rear wheel HP on the TB really around 210?? :( If it's true, then it losses around 30% of it's rated power! Where is it all going to? My 335i is rated at 306 HP and its rear wheel HP is around 280, that's less then a 10% loss. I know I can't realistically compare the two, but how can the TB loss 3 times the HP? :sadcry:
Its been a long standing rule of thumb that automatic transmissions (in their stock form) lose on average 25% of the engine horsepower. Add a transfer case to the equation and its even more.

Manual transmissions lose MUCH less. So is your 335i an automatic? If it is then that 305 hp is very underrated. Car companies have been known to do that to get around various rules at various times.

AG
 

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Discussion Starter · #5 ·
Its been a long standing rule of thumb that automatic transmissions (in their stock form) lose on average 25% of the engine horsepower. Add a transfer case to the equation and its even more.

Manual transmissions lose MUCH less. So is your 335i an automatic? If it is then that 305 hp is very underrated. Car companies have been known to do that to get around various rules at various times.

AG

It's a manual. I think you're correct on the HP rating in the 335i. I've read BMW under rated it so it would not compete against the E46 M3. BMW's 0-60mph time is 5.3 seconds, while most car reviews tests ran 4.8-5.0 seconds.

It would have been nice if GM would have put a 6 speed transmission and e-fans.
 
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